1. Field of the Invention
The present invention relates to a semantic analysis apparatus, a semantic analysis method, and a semantic analysis program, according to which meaning of a term used in a sentence of natural language is analyzed.
2. Description of the Related Art
Conventionally, researches have been widely carried out on natural language processing, in particular on semantic analysis. In the natural language processing, meaning of words used in sentences of natural language is analyzed. An ultimate goal of such researches is to bring out a computer which understands human language.
For example, according to one semantic class analysis technology, sentences written on a target subject are analyzed based on a morpheme dictionary featuring 280,000 words and properties, i.e., 106 kinds of semantic classes and definitions of co-occurring words, included in the morpheme dictionary (see, for example, “A MultiModal Help System based on Question Answering Technology” Information Processing Society of Japan Technical Report, Digital Document, No. 36, 2004).
Further, according to processing disclosed in Japanese Patent Application Laid-Open No. 2001-325284, for example, only a table is set as an analysis target, and a class is determined based on an instance with the use of ontology. Thus, an attribute name region and an attribute value region are extracted. Another disclosed technique allows for classification of words based on the ontology (see, for example, U.S. Pat. No. 6,487,545).
The conventional techniques as described above, however, are disadvantageous in that they carry out the semantic analysis generally at the relevance ratio as low as 60 to 70%. Furthermore, a rule creation and maintenance thereof are complicated.